1. Field of the Invention
The present invention relates to the structure of a coil bobbin used in rotary transformers and the like such as various motors and resolvers.
2. Description of the Related Art
As shown in FIG. 6, a coil bobbin 101 used in rotary transformers and the like such as various motors and resolvers, is constituted by forming flanges 104 and 105 at both ends in the axial direction of a cylindrical winding drum portion 103 of a bobbin main body 102, wherein at a portion of one of the flanges 104, a terminal support 106 is provided as a single piece protruding in the outer direction of the diameter direction, the terminal support 106 being provided with 2 terminal pins 107 that are standing, at the same time, both ends of a wire 109 that is wound around the outer circumference of the winding drum portion 103 of the bobbin main body 102, are respectively wound and fixed by soldering or the like to the terminal pin 107 (Refer to Patent Publication Hei.9-224342).
However, since in the coil bobbin 101 of the prior art shown in FIG. 6, a structure was adopted in which the extremities of the winding start and the winding ends of the wire 109 are directly wound and fixed to the terminal pins 107, the extremities of the winding start and the winding ends of the wire 109 rise to the terminal pins 107 as shown in the FIG., unavoidably generating a straight rising portion 109a that does not follow the arc, and particularly in a resolver and the like, in case said coil bobbin 101 is to be covered with an outer core made of metal (not shown), the rising portion 109a of the wire 109 contacts the outer core, causing difficulties.
Therefore, a structure was adopted, in which the extremities of the winding start and the winding ends of the wire 209 are intersect in an X-shape at the base end portion of the terminal support 206, as shown in FIG. 7 and FIG. 8 (partial perspective view in the direction of arrow E of FIG. 7).
However, there was the problem that when the extremity portions of the winding start and the winding ends of the wire 209 intersect as described above, the wire 209 contacts with itself at the intersection, and due to oscillations, shocks and the like, the coat at the contact portion of the wire 209 wears off, or scratches occur on wire 209, inducing deterioration of the insulating withstand voltage or short circuit.
Therefore, a structure as shown in FIG. 9 was proposed, which prevents intersection of the winding start and the winding ends of the wire. That is, FIG. 9 is a partial perspective view of the terminal portion of the coil bobbin 301, in which 2 terminal pins 307 are provided to the terminal support 306 so as to be standing in the horizontal direction, and at one portion of the terminal support 306, an engaging protrusion 306a and a guide protrusion 306b are formed integrally.
Therefore, one end 309a that is the winding start of the wire 309 wound around the coil bobbin 301 is guided along the guide groove 306b-1 formed in the protrusion 306b to one terminal pin 307, then wound and fixed to said terminal pin 307, the other end 309b that is the winding end of the wire 309 is hooked to the engaging protrusion 306a and guided to the other terminal pin 307, then wound and fixed to said terminal pin 307, such that according to this structure, crossing over of wire 309 can be avoided.
However, with the above-mentioned structure, since the shape of the coil bobbin 301 is complicated, there is the problem that automatic winding of wire 309 by automatic winding machines becomes difficult.